1. Field of the Invention
The invention relates to drive systems, and more particularly to drive systems for food slicing machines in which a food product retaining carriage is reciprocatingly driven.
2. Description of the Related Art
In conventional food slicing machines, a workpiece-retaining carriage is reciprocatingly driven for the purpose of reciprocating a food product workpiece, such as a cheese log, through a cutter. The workpiece is cut, forming a slice that falls downwardly due to gravity onto a conveyor, a tray or another food product, such as a slice of bread or pizza crust. After the slice is formed, the workpiece is driven back across the cutter, dropping downwardly so that another slice can be formed. The operation of the slicing machine is cyclical, with a cutting stroke during the first half of the cycle and the return stroke in the second half of the cycle.
The workpiece-retaining carriage is linked to a drive mechanism. Conventional drive mechanisms are hydraulic rams, and cranks connected to rotary motors, both of which are described in U.S. Pat. No. 4,436,012. Both of these drive mechanisms mount to the workpiece-retaining carriage near where the food product is retained. This configuration has the disadvantage that drive system parts and lubricants must be made of food grade materials, and must be washable by the means used to wash the carriage.
The displacement of the carriage by the rotary motor and crank mechanism approximates sinusoidal motion. This sinusoidal motion has large variations in the speed of the workpiece during the formation of slices. These large variations result in inaccuracies in the formed slices.
Additionally, the width of the motor and crank mechanism is greater than the width of the carriage. This configuration makes placing multiple carriages in a close, side-by-side relationship unfeasible.
Therefore, the need exists for a carriage drive system that can be adjusted to control the accuracy of formed slices. The drive system should also be mounted in a position that keeps moving parts away from the region of the food product workpiece to avoid the necessity of expensive materials and frequent washing. Furthermore, the drive system should be narrow enough that several carriages can be mounted in close proximity without interference between moving parts.
The invention is an improved drive system for a food product slicing machine. The slicing machine with which the drive system cooperates has a frame, and a workpiece-retaining carriage attached to the frame. The carriage retains a food product workpiece therein, and reciprocates the workpiece through a path including a cutter.
The drive system includes a drive member pivotably mounted to the machine frame about a pivot, such as a pivot pin. A support panel mounts to the drive member, and has a curved surface spaced from the axis. This space is substantially equal to a radius of curvature of the curved surface. The curved surface has first and second sides.
First and second idle pulleys are connected to the machine frame, with the second idle pulley spaced from the first, forming a gap. A drive pulley is drivingly linked to a rotatably driven shaft of a prime mover, preferably through a gear mechanism. An elongated, flexible drive means, preferably a belt, loops around the drive and idle pulleys. The first end of the drive belt extends from attachment to the drive member, near the first side of the support panel""s curved surface. The belt extends through the gap between the first and second idle pulleys, around the drive pulley, and through the gap. The second end attaches to the drive member near the second side of the support panel""s curved surface.
When the prime mover""s shaft rotates in one direction, the drive belt is driven in the same direction, applying a force to one side of the support panel and drive member. The drive member is displaced in one direction, pivoting about the pivot axis and swinging the workpiece-retaining carriage through an arcuate path. Upon reaching its extreme, the prime mover stops the drive shaft""s rotation and reverses its direction, thereby swinging the workpiece-retaining carriage through the arcuate path in the opposite direction.
By continuously reversing the prime-mover""s direction of rotation, the workpiece-retaining carriage is reciprocated through the arcuate path, thereby reciprocating a food product workpiece retained within the carriage through a cutting blade, forming slices. The prime mover provides a much more consistent velocity during cutting, which results in consistent slice thickness and spacing of multiple slices. Furthermore, because of the configuration of the drive system, several workpiece-retaining carriages can be mounted in a small space.